1. Department of Mathematics, Honghe University, Mengzi, Yunnan 661100, China
2. Department of Mathematics, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China
3. School of Mathematics and Statistics, Hunan University of Technology and Business, Changsha, Hunan 410205, China
4. Key Laboratory of Hunan Province for Statistical Learning and Intelligent Computation, Hunan University of Technology and Business, Changsha, Hunan 410205, China
5. School of Mathematics and Statistics, Central South University, Changsha, Hunan 410083, China
6. School of Mathematics and Physics, North China Electric Power University, Beijing 102206, China